Here in Canada it would be very strange to be referred to in a normal situation as sir or ma'am - ultra polite and formal. Usually those terms are only used in the military, with police, or a retail/business setting, not in day to day relationships or family. I can't even imagine calling my parents sir or ma'am, so distant and formal in our vocabulary. I would say it is definitely a regional thing and if you do not agree then you need to come to an agreement with your DH on when to use it - maybe with the grandparents that expect it and other elders?

Exactly what I was thinking!!! (I'm also Canadian). My kids would get a stink eye if they ever refered to anyone as sir or ma'am. I'm tryign to teach Mr or Mrs. (last name) but if it's casual and asked for then they can call first name basis too (like our neighbours) We are Tim and Erin to their dsughter and they are Jay and Amanada to ours.